The key component of a digital PAL or NTSC color decoder is a quadrature demodulator for these AM modulated signals. For a SECAM color decoder, however, an FM demodulator is required which is conventionally implemented using a Hilbert filter which is followed by a CORDIC processor (coordinate rotation digital computer) and a differentiation stage. EP-A-0 597 160 discloses a corresponding digital stand-alone SECAM decoder. A CORDIC processor is described in more detail in EP-A-0 329 812 and EP-A-0 597 160 and in an article cited therein.